035 Characterization of a murine model of dermatitis induced by oxazolone

Atopic dermatitis (AD) is a chronic, relapsing, inflammatory skin disease characterized by pruritus and eczematous lesions. It has been described that the repeated topical application of hapten oxazolone to ears sensitized mice cause lesions mimic some features AD. However, in most published reports number challenges significantly high (6 12), which translates into long duration assay causing significant distress animals. In present study we have model induced 4 applied on days 7, 9, 11 14 post-sensitization. Ear samples were obtained day 15. Using this protocol, main clinical signs consist an increase ear thickness erythema. Histological analysis reveals presence diffuse, moderate acanthosis with frequent areas parakeratosis pustules. A dermal infiltration macrophages, lymphocytes polymorphonuclear cells, as well proliferation fibroblasts also observed. Skin biopsies show increased levels mRNA expression cytokines, including Th2 markers IL-4, IL-13, IL-22 IL-31, reduction loricrin, indicating barrier disruption. To further validate model, assessed effect commercial formulations anti-inflammatory drugs betamethasone, tacrolimus crisaborole. The three treatments able reduce thickness, erythema IL-13 IL-33, whilst increasing loricrin. Of note, betamethasone inhibited whereas it crisaborole had no at all. Overall, our results replicates several AD respond approved drugs, making suitable for screening purposes.